Medical or veterinary injection device

ABSTRACT

The device includes a handpiece 1, its handle-shaped portion constituting an under pressure air receptacle 2. The handpiece 1 contains a pneumatic jack 15 fed by means of a pressure reducing valve 11 with constant air under pressure derived from the receptacle 2. The jack 15 pushes against a recall spring a catapult 16 bearing an injection needle 21. The piece 1 also bears a movable syringe 23 containing the liquid and connected to the needle 21 by a flexible pipe 22. A piston 29 moving in the syringe 23 is propelled by the air of a pressure chamber 35 fed from the receptacle 2 through a second pressure reducing valve 30. A squeezing piece 25 brings about a flattening of the pipe 22 by prohibiting the flowing of the liquid and it is pushed back at the outlet end of travel of the jack 15 so as to free the pipe 22 from squeezing.

The invention concerns veterinary or medical devices and moreparticularly the injection of liquids into living tissues with the aidof a hollow needle which moves the liquid under low pressure as far asits end implanted in the derm or flesh. Another sector concerned is theprocessing of foodstuffs.

A number of devices have been produced able to replace the hand of themedical practitioner for implanting the needle and injecting the liquid.The purpose of these devices is to prevent the patient from experiencingpain during implantation or injection and avoid the operator frombecoming tired. However, up until now, these devices have not beenentirely satisfactory as they are too heavy, expensive and inadequatelyprotected against the risks of transmitting infection from one patientto another.

For example, the U.S. Pat. No. 4,790,823 granted 13 Dec. 1988 in thenames of CHARTON and GASQUET describes a device comprising a handpiececonnected by a flexible pipe to a console placed on the floor, theconsole providing the handpiece with compressed air or the electriccurrent and even possibly the liquid to be injected under pressure. Thisliquid originates from a syringe whose piston is propelled by a screwactivated by an electric micromotor. However, the console takes up anexcessively large amount of space and is expensive, and the handpiece,although light in itself, is connected to it by a compressed air pipeand possibly an electric wire which interferes with its handling.

The French Patent No 78.08827 (published under U.S. Pat. No. 2,401,667)in the name of ISLAND S. R. L., describes a similar device where thepiston of the syringe fitted with the needle and borne by the handpieceis propelled by a pneumatic jack fed with compressed gas by a flexiblepipe connected by a quick-dismantable connector to a pressure reducingvalve which equips an under pressure gas receptacle distinct from thehandpiece. Here again, the pipework interferes with the handling of thehandpiece which is not autonomous during injections. In addition, thecatapult bearing the needle and syringe is quite heavy which requires arelatively high pressure so as to feed the jack and thus requiresconsiderable consumption of compressed air limiting the autonomy of thedevice. Secondly, the pneumatic jack, which propels the piston of thesyringe so as to inject the liquid, receives pressure adjusted by avariable section orifice which makes the speed of injection and thus thevolume injected dependent on the manual skill of the operator.

The French Patent No 84.11336 (published under U.S. Pat. No. 2,567,760)in the names of HIBON and KABLA describes an autonomous pistol-shapedhandpiece whose handle contains a movable under pressure gas bottle.Here again, the catapult bears the needle and syringe and is againrelatively heavy, and secondly the propulsion of the piston of thesyringe is ensured by the same jack as that of the catapult which doesnot allow the injection pressure to be adjusted.

The aim of the present invention is to resolve the drawbacks inherent inknown devices and to this effect offers an injection device comprisingsufficient autonomy for medical practice allowing for precise andpainless implantation and injection and reducing operator fatigue whilstlending itself to rigorous aseptic treatment.

In order to achieve the above, the device of the invention isconstituted by a handpiece containing firstly a pneumatic jack designedto propel against a recall spring a catapult bearing an injectionneedle, and secondly a movable syringe containing the liquid andconnected to the needle with in addition a pneumatic member forpropelling a mobile piston into the syringe, the jack and pneumaticmember being fed by a given receptacle equipped firstly with a pressurereducing valve delivering gas at constant pressure to the jack, andsecondly a variable section orifice delivering the under pressureadjustable gas to the pneumatic member, the invention beingcharacterized in that the variable section orifice forms part of asecond pressure reducing valve which delivers the gas at stable andadjustable pressure to the pneumatic member, and in that the handpiececontains the receptacle, the pressure reducing valve at constantpressure and the second pressure reducing valve.

The device preferably has the shape of a pistol whose handle constitutesthe compressed gas receptacle so as to have the maximum availablevolume. The compressed air is produced by a small independent connectedcompressor for filling the receptacle with the aid of a fast connectorwhich may be of any known type.

The device of the invention, according to the information contained inthe U.S. Pat. No. 4,790,823 mentioned earlier, again preferably uses alight accurate catapult bearing solely the needle, the latter beingconnected by a thin flexible tube to a syringe fixed to the handpiece,the needle and syringe unit not being able to be separated and beingdisposable after use.

So as to reduce to the maximum the weight and spatial requirement of thedevice, the pneumatic member for propelling the liquid is preferably apressure chamber to which the syringe is imperviously secured so thatthe pneumatic pressure directly pushes the piston into the syringe.

So as to clearly understand the device of the invention, there nowfollows a non-restrictive example of a preferred embodiment withreference to the accompanying drawing on which:

FIG. 1 is a longitudinal vertical cutaway view of an injection deviceaccording to the invention,

FIG. 2 is a partial cutaway top view of the device of FIG. 1,

FIGS. 3a and 3b are lateral views of a syringe equipped with a freepiston and provided with its filling tooling, said piston being shownrespectively at the zero graduation of the syringe and at the fullfilling position of the syringe, and

FIG. 4 is an enlarged longitudinal cutaway view of a variant of thesqueezing device.

With reference more particularly to FIG. 1, the device of the inventionis formed of a handpiece made up of a body 1 extended by a handle 2, thelatter forming a receptacle closed by a covering cap 3 held down byscrews, such as 4, with a gasket 5.

The covering cap 3 comprises a filling connector 6 with a joint 7intended to cooperate with a filling tube (not shown) and derived froman air source compressed at 9 bars, for example. The connector 6 isequipped with a nonreturn valve formed of a ball 8 able to be applied bythe internal compressed air pressure to a seat 9 via an autoclave effectonce the filling tube has been removed. A small spring 10 is providedfor pushing back from the outside the ball 8 against any internalpressure lower than a minimum pressure determined by the one below whichthe functioning of the device would not be satisfactory, such as below2.5 bars. This then causes the receptacle to be drained, thus indicatingthe need to refill it.

The body 1 contains a first pressure reducing valve 11 directlyconnected to the receptacle 2 by a pipe 12 so as to discharge the air ata pressure of 2.5 bars, for example, by a pipe 13. A three-way valve 14connected to this pipe 13 and opened by activating a push-button sendsair via a pipe 13' and a connector 13" into the jack 15 of a catapult16. The latter is borne by the rod 17 of the jack 15 and by a lip seal18 embedded at the end of an externally threaded guide 19 screwed into alinking tube 20 secured to the body 1 and bearing the jack 15 at itsother end. The jack shown uncut is externally threaded and contains arecall spring. The lip seal 18 prevents the inside of the linking tube20 from being polluted by oozings of the injection liquid which couldfall back along the injection needle 21.

This needle 21 is sealed onto a joining piece 21' kept on an open cradlewhich extends the catapult 16 and which is relatively elastic so asallow for this holding. Passing through the opening of the cradle is alinking tube 22 secured at one end to the joining piece 21' and at theother end to a graduated syringe 23 containing the liquid to beinjected. All these elements are delivered after aseptic treatment andare disposed of after usage without separating them.

The tube 22, known as a catheter, is thin and flexible. The operator,once the needle 21 and the syringe 23 have been installed, makes thistube 22 penetrate into a slit 24 transversally indenting the linkingtube 20. Placed inside the latter and around the catapult 16 is a mobilering 25 which is stressed towards the slit 24 by a spring 26 so that itacts as a squeezing device able to flatten the tube 22 and thus preventflowing of the liquid to be injected from the syringe 23 to the needle21. When the jack 15 is activated, a thrustor 27 formed of a washercompacted between the rod 17 and the catapult 16 abuts against themobile ring 25 by pushing it back against the spring 26. The squeezingof the tube 22 is thus suppressed at the end-of-travel of the catapult16 which has implanted the needle 21 at the desired location andinjection of the liquid then takes place.

When the valve 14 is released, it aerates the jack 15 with fresh air,the latter returning to its retracted position under the action of itsinternal spring. The mobile ring 25, pushed back by its spring 26,returns to squeeze the tube 22 which stops injection before the needle21 is removed. At the periphery of its squeezing face, the mobile ring25 comprises a narrow projection 25' to flatten the tube over a smallsurface, thus making it possible to reduce the force of the spring 26and thus the pressure in the jack 15 to the advantage of the autonomy ofthe device. The thrustor 27 is lined with rubber toroids which dampenthe impacts against the mobile ring 25 and against the face of the jack15 which reduces operating noise.

FIG. 4, which shows a variant of the squeezing device, also shows thejack 15, the linking tube 20 with its slit 24, the mobile ring 25forming the squeezing element, the spring 26, and the stop 27 fixed atthe rod of the jack to which the catapult 16 is screwed, the lattersliding into the joint 18 borne by the guide 19. Here, the ring 25 doesnot comprise a peripheral flattening projection but is extended by a rod40. This rod is guided with a small amount of play into a shoulder 41 ofthe linking tube 20 so as to penetrate into the throat 24 which does notopen inside this tube.

The resting of the rod 40 on the catheter previously introduced to thebottom of the slit 24 is then immediate which allows for the use of aneven weaker spring and thus less pneumatic pressure in the jack 15.

It shall be noted that the slit 24 preferably comprises an inlet widthslightly smaller than the diameter of the catheter which is made topenetrate into it by means of elastic expansion, whereas its bottom is aperforation transverse to the diameter of the catheter which makes itpossible to ensure that the latter is in the correct position oppositethe rod 40 as it is then able to slide freely inside this perforation.

The bottom of the slit 24 does not open into the bore of the tube 20 sothat the slit and catheter remain outside and thus no external pollutioncan seep inside the mechanism.

The fresh air aerating of the jack 15 may be slowed down by a diaphragm28 borne by the valve 14 so that the removal of the needle 21 isgradual, thus allowing for a distribution of the liquid along the path.This diaphragm is preferably adjustable by any suitable known device andit may consist, for example, of a check screw traversing the wall of thebody 1.

The pressurizing of the liquid to be injected results from a pneumaticmember for thrusting on the piston 29 contained in the syringe 23. Thismember is fed from a connector 13" by a pressure reducing valve 30discharging with a stable adjustable pressure in a pipe 31. Thisadjustment depends in particular on the viscosity of the liquid to beinjected and is effected by a knurled button 33. A nonreturn valve 32may possibly be interpositioned.

Instead of using a jack to propel the piston 29, according to theinvention, direct thrusting of stable adjustable air derived from thepressure reducing valve 30 is preferably used on this piston. To thiseffect, the syringe 13 is pressed against a gasket 34 and retained viaits small ring 34' against a pressure chamber 35 inserted in the body 1.

FIG. 1 shows an embodiment of a piston 29 adapted to this pneumaticthrusting mode. Instead of a piston rod able to be propelled manually, athin rod 36 is fixed to the piston so as to solely be used on tractionof the piston for filling of the syringe. In addition, this rod 36comprises embrittlement throats 36' making starts of rupture so as to bedivisible close to the small ring 34' of the syringe in order to avoidno reaching the bottom of the capacitor 35. The operator, once thesyringe has been filled up to the desired graduation, then breaks thisrod 36 and secures the syringe to the capacitor 35. After theinjections, the syringe, whose piston 29 has become inaccessible isremoved, which avoids the unit (syringe 23, catheter 22 and needle 21)being used again to the advantage of the aseptic treatment of subsequentwork interventions.

According to a variant shown on FIGS. 3a and 3b, the piston 29' is freeand does not bear any rod. The syringe 23 is delivered with this piston29' at zero graduation and with a second contiguous piston 38constituting a disposable tool provided with a traction rod 38' (FIG.3a). By means of acting on this rod, the two pistons 29' and 38 movetowards the opening of the syringe until the tooling piston 38 opensoutside the latter. Then the piston 29' is flush with its small ring andthe syringe is completely filled and is ready to be secured to thecapacitor 35.

It is to be noted that this capacitor 35 is small and much lighter thana jack having the same length as the syringe. Thus, according to onevariant (not shown on the drawing), the pressure chamber 35 and thus thesyringe 23 could be secured to the catapult 16 without increasing theweight of the mobile unit.

Also shown on FIG. 1 is an element 37 which surrounds and protects theneedle 21. This element 21 is scalloped at one end so as to leave theneedle 21 visible and guide the operator as regards the penetrationpoint of this needle. The element 37 is screwed via the other end ontothe fixed guide 19 which makes it possible to adjust the penetrationdepth of the needle 21. A counternut 39 shown on FIG. 4 is able to lockthis scalloped element 37.

The description given above has been given by way of non-restrictiveexample and constructive additions or modifications could be madewithout departing from the context of the invention.

We claim:
 1. Liquid injection device constituted by a handpiece (1)containing firstly a pneumatic jack (15) designed to propel against arecall spring a catapult (16) bearing an injection needle (21), andsecondly a movable syringe (23) containing the liquid and connected tothe needle (21) with in addition a pneumatic member (35) for pushing amobile piston (29) into the syringe (23), the jack (15) and thepneumatic member (35) being fed by a same receptacle (2) equippedfirstly with a pressure reducing valve (11) delivering a gas at constantpressure to the jack (15), and secondly a variable section orificedelivering an adjustable gas under pressure to the pneumatic member(35), wherein the variable section orifice forms part of a secondpressure reducing valve (30) which delivers the adjustable gas at stablepressure to the pneumatic member (35) and wherein the handpiece (1)contains the receptacle (2), the pressure reducing valve at constantpressure (11) and the second pressure reducing valve (30).
 2. Deviceaccording to claim 1, wherein said receptacle (2) constitutes a handleof the handpiece (1).
 3. Device according to claim 1, wherein thereceptacle (2) comprises an autoclave nonreturn valve (8) which ispropelled from outside by a spring (10) which lifts up the valve (8) anddrains the receptacle (2) for any internal pressure less than a specificminimum pressure.
 4. Device according to claim 1, wherein the handpiece(1) comprises a manual pushbutton valve (14) whose thrust ensures thefeeding of the jack (15) for propelling the catapult (16) and whosefreeing ensures the fresh air aeration of said jack (15).
 5. Deviceaccording to claim 4, wherein the fresh air aeration of the thrust jackis effected through a small orifice so as to slow down the return of theneedle (21).
 6. Device according to claim 1, wherein the catapult (16)is coaxially borne by the pneumatic jack (15) and by an end guide (18)close to the needle (21).
 7. Device according claim 1, including asecond device for stopping the flowing of the liquid on the connection(22) between the syringe (23) and the needle (21).
 8. Device accordingto claim 7, wherein said connection is a flexible pipe (22), whereinsaid stopping device comprises a squeezing element (25) with a spring(26) which brings about a flattening of the pipe (22) and wherein anopening pushbutton (27) distances the squeezing element (25) against thespring (26) at the end-of-travel of the catapult (16) propelled by thejack (15).
 9. Device according to claim 8, characterized by a transverseslit (24) fitted in a fixed tube (20) surrounding the catapult (16),said fixed tube containing the sliding squeezing element (25) pushedback at the end-of-travel of the pneumatic jack (15) so as to free fromsqueezing the flexible pipe (22) previously introduced into the slit(24).
 10. Device according to claim 9, wherein the squeezing element(25) comprises a narrow peripheral projection (25') for flattening theflexible pipe (22) over a small surface.
 11. Device according to claim8, wherein the squeezing element (25) activates a rod (40) traversingwith a small amount of play a fixed tube (20) so as to flatten the pipe(22) outside said tube (20).
 12. Device according to claim 1, wherein anonreturn valve (32) is inserted between the first pressure reducingvalve (11) and the pneumatic member (35).
 13. Device according to claim1, wherein the pneumatic member is a pressure chamber (35) cooperatingimperviously with a small ring (34') of the syringe (23) so as todirectly propel the piston (29) after the syringe (23) filled withliquid has been secured to said chamber.
 14. Device according to claim13, wherein the syringe (23) comprises a piston with a liquid suctionrod (36) which has embrittlement throats (36') able to be broken so thatthe portion of the rod (36) emerging from the syringe can be disposed ofonce said syringe has been filled and before it has been secured to thepressure chamber (35).
 15. Device according to claim 13, wherein thesyringe (23) comprises a free piston (29') and wherein its filling iseffected via the traction of the rod (38') of a tooling piston (38)contiguous with the free piston (29') and wherein it is removed beforethe filled syringe is secured to the pressure chamber (35).
 16. Deviceaccording to claim 1, wherein the syringe (23), the needle (21) andtheir connection (22) form a fixed disposable unit.
 17. Device accordingto claim 1, wherein a tubular element (37) surrounds and protects theneedle (21) when the catapult (16) is inactive, said element (37) beingscalloped at one end and fixed at the other end around a guide (19) ofthe catapult (16).
 18. Device according to claim 1, wherein the syringe(23) is borne by the catapult (16) secured to the pressure chamber (35).